Over past several years, tremendous progress has been made in X-ray detector techniques, real-time/volumetric CT algorithms, and computing resources. Development of a volumetric CT fluoroscopy (VCTF) system for small animal studies has just become commercially feasible. Our long-term goal is to make volumetric CT fluoroscopy a vital tool in biomedical laboratories for various applications, especially small animal studies, such as contrast-enhanced dynamic imaging for diagnosis and treatment of tumors. The objective of this project is to develop such a prototype system and demonstrate its feasibility and utility in small animal studies. The specific aims for the phase I of this project are to (1) design a prototype VCTF scanner, (2) develop a Feldkamp-type software package for the scanner, (3) optimize system/algorithm parameters in numerical simulation for the Phase II development. In the Phase II, we will construct the prototype VCTF system, combine Feldkamp-type and ordered-subset reconstruction algorithms, integrate the hardware and the software, characterize the system in phantom experiments and in animal experiments. In Phase III, we will complete the engineering design to meet the production requirements, and commercialize the VCTF system. PROPOSED COMMERCIAL APPLICATIONS: The proposed volumetric CT fluoroscopy system represents a significant advancement in the CT field. This system utilizes state-of-the-art detector techniques and modern image reconstruction methods, provides volumetric and continuous imaging capabilities with high spatial, contrast and temporal resolution, has not only important and immediate applications in small animal imaging but also clear and major potentials in industry and other areas. Therefore, this system should be highly profitable.